Transparent, Conductive Movie Helps Put Electronics In Print

A film that avoids car windows from steaming up in winter season. A screen that reacts to commands at the touch of a finger. Products made by Germany-based PolyIC may be found in any of these applications; the company specializes in printed electronic devices. Its transparent, conductive movie called PolyTC remains in numerous displays and other applications.

Making use of a roll-to-roll process, the company prints electronics with ultra-thin metal finishings. The printing material, or substrate, is a transparent polyester film. A number of various materials, or “ink,” are transferred on the substrate in a liquefied state. These inks include semi-conductive, conductive and insulating plastics as well as various metal compounds. Constant roll-to-roll procedures like these are low-cost and use the needed structure directly, during the manufacturing process.

Modern printing processes deposit very thin metal finishings at a resolution of simply 10 m– one quarter the width of a human hair. Standard printing processes have resolutions in a range of more than 100 m. In electronics nevertheless, printing resolutions of under 20 m are being sought since the resolution in the printing procedure actively affects the electrical performance of the last product. This is how the device prints optically transparent films that are, at the exact same time, electrically conductive.

Indium tin oxide (ITO) is frequently utilized for applications like these. Yet, the innovation behind ITO does have downsides. ITO coverings are rather brittle and fairly expensive. That’s why the design team at PolyIC had to come up with a versatile and economical option. To develop PolyTC, designers had to conquer numerous hurdles, specifically in production and processing technology.

The tensile stress on the substrate roll had a substantial influence on the accuracy of the production process. A certain pattern in transport habits emerged, depending on the substrate’s density and product. To accomplish a high-precision, steady web, PolyIC installed Rexroth’s IndraMotion system, combining the Motion Control and PLC in a single control device.

Integrated functions, like tensile anxiety and winding controls, assisted accelerate personalization to match individual requirements. Exact registration was crucial to making sure the electric structures truly worked. This identified how accurately the individual ink colors were positioned in relationship to each other.

Areas of different sheet stress were linkedconnected to each other by the sheet itself and had to be managed simultaneously. Required and accurate controls demand intricate decoupling of numerous cascaded stress control units.

Engineers integrated the procedure control device with the device controls to address this problem. Exact execution of a complex guideline was attained by real-time integration of procedure controls and controling sheet movement with the IndraMotion system solution. Maintaining sheet tension was enhanced threefold. That enhancement represented an enormous advance in process stability. The film sheet had to be stopped throughout production so that high-precision testing equipment could keep track of electrical functions.

To this end, IndraMotion integrated the rolling movement of the web feed with the linear movement of a sled. The sled in the so-called web accumulator travels at the very same speed as the sheet, however in the opposite instructions, and effectively stops the web. This implies that a part of the web stands still for a moment for electrical testing, without needing to bring the whole assembly line to a halt and without compromising efficiency.

Bosch Rexroth
www.boschrexroth.com